Delta receptors have been identified as having a role in many bodily functions such as central nerve and pain systems. Delta agonists have shown many therapeutic activities towards pain, anxiety, depression and other central nerve and pain related symptoms.
U.S. Pat. No. 6,187,792 to Delorme et al. describes some delta agonists that are useful in treating pain and central nerve related diseases. However, there is a still need for improved methods of preparing these compounds and new polymorphs of these compounds.